Electrical heating apparatus



y 16, E. N. CALHOUN 2,158,602

ELECTRICAL HEATING APPARATUS Filed April 13, 1937 l I I47 ii 1M vzm TOR, BTfiw, MM M A11 ORNEYS Ertusi N. Cdl houn- Patented May 16, 1939 UNITED STATES ELECTRICAL HEATING APPARATUS Ernest N. Calhoun, Pittsburgh, Pa assignor, by

means assignments, to Edwin L. Wiegand, Pittsburgh, Pa.

Application April 13, 1937, Serial No. 136,587

22 Claims.

My invention relates to electrical heating apparatus, and more particularly to such apparatus of the forced convection or circulation type, and the principal object of my invention is to provide new and improved electrical heating apparatus of these types.

In the drawing accompanying this specification, and forming part of this application, I have shown, for purposes of illustration, several forms which my invention may assume. In this drawing:

Figure 1 is a plan view of a unitary cell embodying my invention,

Figure 2 is a section taken along the line 2--2 of Figure l,

Figure 3 is a fragmentary view, in longitudinal section, of heating apparatus embodying my invention, and shows one way in which cells such as shown in Figures 1 and 2 may be utilized,

Figure 4 is a view, partly fragmentary, in longitudinal section, showing heating apparatus embodying my invention and-illustrating another way in which the unit cells shown in Figures 1 and 2 may be utilized,

Figure 5 is a fragmentary sectional view taken along the line 5-5 of Figure 2, and

Fi ure 6 is a section, partly fragmentary, taken along the line 6-6 of Figure 5.

Referring first to the unitary cell of Figures 1 and 2, the cell here illustrated comprises an electrical heating unit l0 here shown as disposed between spaced wall members I, I2. The electrical heating unit comprises a general body portion l3 and heat dissipating means H provided thereon, the heat dissipating means H extending transversely between thewall members l2.

The general body portion l3 of the heating unit is here shown as of oblong cross-sectional outline. The primary body portion is in the form of an electric heater I5 of the strip type, but not of rectilinear form, and is here shown as including a sheath comprising a sheet metal channel having a bottom wall l5 and side flanges l1, l8 along with a longitudinally extending strip of sheet metal l9 closing the open-side of the channel, the free ends 20 of the flanges i1, it being bent against the outsideof the closure strip l9.

Disposed within the sheet metal sheath of the strip heater I5 is a resistor 2| which is here shown as a strip of electrical resistance material, the strip being of undulating form and extending longitudinally within the sheath one or more times as may be desired. Itwill be understood that the resisitor 2| may be of any other suitable form. The resistor 2| is insulated from the sheath by insulation 22 disposed within the sheath and in which the resistor is embedded. The insulation 22 is desirably refractory and in particular highly compacted granular refractory material, which, while electrically insulating, is heat conducting.

The heat dissipating means it here shown comprises fin means. The fin means may be of any suitable form. In the illustrated embodiment the fin means includes a plurality of fin elements 23 spaced longitudinally of the general body portion I3 and extending transversely thereof. Each fin element 23 is, in this instance, integral with one end of an annular collar 24 which is of such form and dimensions as to fit snugly but slidably over the sheath of the strip heater I5. .The end of each collar 24 at which the fin element 23 is provided has an opening which has a recess or outward flare 25, and the end 26 of-the adjacent collar 24 is adapted to wedge into the recess or flare 25. If desired the end 25 may be slightly beveled to promote entrance of the end 26 into the recess or flare 25.

The fin elements 23 are here shown as of oblong rectangular outline.

One end of the strip heater I5 is here shown as provided with a pair of terminals 21, 28, one of which, 21, is shown in side elevation in Figure 1 and the other of which, 28, is directly behind the terminal 21. The terminals 21, 28 are connected within the sheath to the resistor 2|.

In making such a heating unit in as shown in Figure l the primary body portion, constituted by the strip type heater i5, may be first completed in the form of a rectilinear strip heater, this strip heater being entirely completeand comprising all of the constructional features hereinbeiore pointed out with respect to the strip type heater I5, with the exception that the body portion is rectilinear. The finned elements constituted by the collars 24 and fin elements 23 may be then telescoped over the strip heater, and, desirably, enough finned elements are telescoped onto the strip heater so that substantially the entire length of the heater is occupied by finned elements. The last, or both the first and last finned element telescoped onto the heater may, if desired, be brazed to the sheath of the heater, or otherwise suitably fastened thereto. At this stage of the process the heating unit comprises a strip heater provided with heat dissipating means, and the general locus of the heating unit, as determined by the strip heater, is rectilinear. The heating unit is then bent to the form shown in Figure 1 in which, as shown, the unit in forms a complete circle. The adjacent ends of the strip heater l5 are desirably Joined by a weld 23 or otherwise suitably fastened to each other so that the strip heater forms a continuous loop, in this instance circular.

The finned strip heater may be brought to the form shown in Figure 1, manually, by holding the finned strip heater at its ends and' bending itaround some round object, with its wider side against the round object. Another way is to place the finned strip heater between templates or jigs and press it into shape. Pads may be used on the templates in the form of a rubber coating, for example, to keep the fins from skidding and being bent out of proper spacing. Still another way is to pass the finned strip through bending rolls which may be covered with a padding such as rubber. On the other hand, the unit may also be produced by first bending a strip heater to the desired form and then applying the fin means thereto.

The outer wall member, I2, is here shown as formed by the bottom of a channel shaped member 34 having outwardly directed flanges 30, 3|, and in like manner the inner wall member, II, is here shown as formed by the bottom of a channel shaped member 35 having radially inwardly directedflanges 32, 33. Both of the channel shaped members are here shown as of annular form, the radially inside surface of the wall [2 being of such diameter as desirably to fit snugly but slidably over the locus defined by the radially outer margins of the fin elements 23. In like manner the radially outside surface of the wall II is of such diameter as to fit snugly but slidably over the locus defined by the radially inner margins of the fln elements 23. The width of the walls ll, I2 is here shown as approximately the same, but more specifically, somewhat longer than the wider margin of the fin elements 23. The channel shaped members 34, 35 may be formed by casting, each member to form an integral ring of channel shaped cross-section, or these members may be fabricated. If the members-are cast, a desirable metal is aluminum, but other metals may be utilized.

When the heating unit It) has been assembled with the two channel or ring members 34, 35, the heating unit and the ring members may be fastened together as by tack brazing", as shown at the points 36, or otherwise suitably fastened together, as desired. In so tack brazing, or otherwise fastening the parts together, it is not necessary to tack braze every fin element 23 to the adjacent ring member 34, 35, but if desired only a small number of fin elements 23 may be so tack brazed, say at diametrically opposite points of the unit cell.

The outerring member 34 is here shown as carrying a pair of insulated line terminals 31, 38 one of these terminals, 31, being connected by a conductor 39 to the terminal 21 of the heating unit l0, and the other terminal, 38, being connected by a conductor 40, directly behind the conductor 39 in Figure 1, to the other terminal, 28, of the heating unit ill. Conductors leading to a source of current may be of course connected to the line terminals 31, 38, to supply the resistor 2| with current.

The flanges 30, 32, and 3|, 33, serve to readily connect a unit cell, such as shown in Figures 1 and 2, either with conduit means not containing a heating unit or with another unit cell such as shown in Figures 1 and 2. The flanges 32, 33 of the inner ring member, 35, are here shown as provided with'a suitable number .of holes, here shown as four holes 4|, and the flanges 30, ll of the outer ring member, 34, are here shown as also provided with a suitable number of holes, radially alined with the holes 4|, here shown as four holes 42. The holes 4|, 42 in the flanges ll. 33, for example, may be placed in registry with the similar holes in the flanges 30, 32 of an adjacent cell, and the cells fastened together by bolts and nuts 5| cooperating with the registering holes, as indicated inFigure 3.

In Figure 3, three unit cells A, B, C, each such as shown in Figures 1 and 2, are shown assembled, but it is to be understood that a unit cell may be used singly or in association with any desired number of other cells. The three cells A, B, C shown in Figure 3 are here shown as further tied together by tie rods 43, these tie rods passing through registering holes 44 in the flanges 30, 3| of the outer ring member, 34.

In Figure 3 the cell A is shown as having connected thereto a conduit 45, the conduit being provided with a flange 46 having holes registering with the holes 42, 44 in the flange 30 of the outer ring member, 34, and fastened to that flange by bolts and nuts (not visible) and also by the tie rods 43. The conduit 45 may be of any suitable form and extends to a source of fluid under pressure (not shown). Here shown as fastened to the flange 32 of the ring member 35 of unit A is a disc or baffle 41 having holes registering with the holes 4| in the flange 32 and fastened to the flange by nuts and bolts 48 cooperating with the registering holes. The battle 41 is desirably utilized to cause air or other fluid supplied by the conduit 45 to flow, as indicated generally by the arrows in Figure 3, through the annular passage provided by the outer and inner ring members, 34, 35 of the cells A, B, C, thus causing the fluid to abstract heat from the heat dissipating means of these unit cells.

The fluid issuing from the last unit cell, ,0, may be allowed to freely escape therefrom, depending upon the manner in which it is desired to use the heating apparatus, or the heated fluid may enter another conduit means 49 having a flange 50 cooperable with the flange 3| of the outer ring member 34 of the last unit cell, C. The' are bolted together in the manner already explained in connection with the unit cells A, B, C, of Figure 3. As here shown a fan 52 is driven by a motor 53,'the fan 52 operating within an annular wall 54 bolted to the'end unit D. A

baffle 55, similar to the baffle 41, is also provided.'

The cells D, E, F, are here shown as surrounded by a jacket or conduit means 56 having an inlet opening 51; and the left hand end of the conduit means is here shown as'also serving as a housing 53 to lead air to the inlet side of the fan those skilled in the art that each of the illustrated embodiments of my invention provides a new and improved electrical heating apparatus, readily and conveniently constructed and assembled, and accordingly, each accomplishes the principal object of my invention. On the other hand, it also will be obvious to those skilled in the art that the illustrated embodiments of my invention may be variously changed and modified, or features thereof, singly or collectively, embodied in other combinations than those illustrated, without departing from the spirit of my invention, or sacrificing all of the advantages thereof, and that accordingly, the

disclosure herein is illustrative only, and vention is not limited thereto.

I claim:

1. Electrical heating apparatus, comprising: an electrical heating element; a wall spaced from and disposed alongside of said heating element, said wall being provided by the bottom portion of a channel shaped element the flanges of which are directed away from said heating element; and heat dissipating means for dissipating heat from said heating element, said heat dissipating means being fastened to said wall.

2. Electrical heating apparatus, comprising: an electrical heating element the longitudinal locus of which is arcuate; an arcuate wall spaced from said heating element and concentric therewith, said wall being provided by the bottom portion of a channel shaped element the flanges of which are directed away from said heating element; and heat dissipating means for dissipating heat from said heating element, said heat dissipating means being fastened to said wall.

3. Electrical heating apparatus, comprising: an electrical heating element having a body portion having an oblong cross-sectional outline; a wall spaced from said heating element and facing a wider side of said body portion, said wall being provided by the bottom portion of a channel shaped element the flanges of which are directed away from said heating element; and heat dissipating means for dissipating heat from saidheating element, said heat dissipating means being fastened to said wall.

my in- 4. Electrical heating apparatus, comprising:

conduit means so constructed and arranged that it forms a passage annular in cross-section providing a path for the flow of fluid from one end of said conduit means to the other; a heating element disposed in said annular passage and in said path; said conduit means and said heating element being so constructed and arranged that they forni a unitary structure; said conduit means being so constructed and arranged that it may be held to another conduit means forming a continuation of at least the outer wall oi said first named conduit means.

5. An electrical heating unit, comprising: a

- said resistor from said sheath means; said sheath said sheath and comprising longitudinally spaced fin means extending transversely of said sheath.

7. Electrical heating apparatus, comprising: an electrical heating unit including an elongated heating element and heat dissipating means mounted on and unitary with said heating element; a wall spaced from said heating element and contacting said heat dissipating means; said heat dissipating means comprising fin means spaced longitudinally of said heating element and extending transversely of the space between said element and said wall; and means permanently fastening to said wall at least some of the otherwise free ends of said fin means contacting said wall.

8. Electrical heating apparatus, comprising: a plurality of electrical heating units, each unit comprising an electrical heating element and wall means constructed and arranged to leave a space between said element and said wall means thereby to guide fluid through said space and into heat dissipating relation with said element; and means holding an end of the wall means of one unit in approximate abutment with an end of the wall means of an adjacent unit, said holding means and said wall means being so constructed and arranged that said respective wall means jointiyform a composite substantially continuous wall means and that said spaces form continuations of each other to form a continuous passage so that fluid may flow continuously through one space into and through the adjacent space.

9. Electrical heating apparatus, comprising: conduit means including a plurality of sectional units; each of said sectional units having disposed therein and unitary therewith at least one electrical heating element; heat dissipating means mounted on and unitary with each heat element; said heat dissipating means including fin means extending transversely of the respective heating element and longitudinally of said conduit means; and means fastening together adjacent ones of said sectional units so that said sectional units form said conduit means providing a continuous passage through which fluid may be passed and into contact with said heat-- ing elements.

10. Electrical heating apparatus, comprising: an electrical heating unit having a body the gem eral longitudinal locus of which is substantially circular; heat dissipating means on said body, including a plurality of annular members disposed axially adjacent each other about said body, said annular members being respectively provided with a transversely extending flange, the ends of said flanges defining a circle; a cylindrical wall surrounding and contacting said heat.

dissipating means; and means permanently fastening to the inner periphery of said well at least some of the ends of said flanges contacting said wall.

11. Electrical heating apparatus, comprisingr an electrical heating unit including an elongated heating element and heat dissipating means mounted on and unitary with said heating element; a wall spaced from said heating element and contacting said heat dissipating means; said wall being provided by the bottom portion of a channel shaped element the flanges of which are directed away from said heating unit; said heat dissipating means comprising fln means spaced longitudinally of said heating element and extending transversely of the space between said element and said wall; and means permanently fastening to said wall at least some of the ends of said fin means contacting said wall.

12. Electrical heating apparatus, comprising: an electrical heating unit including an elongated heating element the longitudinal locus of which is arcuate and heat dissipating means mounted on and unitary with said heating element; an arcuate wall spaced from and concentric with said heating element and contacting said heat dissipating means; said wall being provided by the bottom portion of a channel shaped element the flanges of which are directed away from said heating unit; said heat dissipating means comprising fin means spaced longitudinally of said heating element and extending transversely of the space between said element and said wall; and means permanently fastening to saidlwall at least some of the ends of said fin means contacting said wall.

13. Electrical heating apparatus, comprising: an electrical heating unit including an elongated heating element and heat dissipating means mounted on and unitary with said heating element; said heating unit having a body portion having an oblong cross-sectional outline; a wall spaced from said heating element and facing a wider side of said body portion and contacting said heat dissipating means; said wall being provided by the bottom of a channel shaped element the flanges of which are directed away from said heating element; said heat dissipating means comprising fin means spaced longitudinally of said heating element and extending transversely fade. l to heat dissipating reiation with said element, said respective wall means being so constructed and arranged that said respective wall means are adapted jointly to form a composite substantially continuous wall means; and means holding said respective wall means so as jointly to form a composite substantially continuous wall means, said holding means being so constructed and arranged that it is attachable to and detachable from said wall means.

15. Electrical heating apparatus, comprising: conduit means so construcmd and arranged that it forms a passage annular in cross-section providing a path for the flow of fluid from one end of said conduit means to the other; a heating element disposed in said annular passage and in said path; said conduit means and said heating element being so constructed and arranged that they form a unitary structure; said conduit means having flange means unitary with the outermost wall of said conduit means and extending outwardly at the respective ends of said wall, said flange means being constructed and arranged for connection to flange means on another conduit means.

16. Electrical heating apparatus, comprising: conduit means including a plurality of sectional units, at least two adjacent units being of substantially uniform cross-sectional outline and disposed with their adjacent open ends co-axial; each of said sectional units having disposed therein and unitary therewith at least one electrical heating element; and means fastening together adjacent ones of said sectional units so that said sectional units form said conduit means providing a continuous passage through which fluid may be passed and into contact with said heating elements.

17. Electrical heating apparatus, comprising:

conduit means including a plurality of sectional units, at least two adjacent units being of substantially uniform cross-section outline and disposed with their adjacent open ends co-axial; transversely extending flanges on said units; each of said sectional units having disposed therein and unitary therewith at least one electrical heating element; and means fastening together adjacent ones of said flanges on adjacent units so that said sectional units form said conduit means providing a continuous passage through which fluid may be passed and into contact with said heating elements.

18. Electrical heating apparatus, comprising: conduit means including a plurality of sectional units, at least two of said units being of substantially uniform cross-sectional outline and disposed with their adjacent open ends co-axial; each of said sectional units having disposed therein and unitary therewith at least one electrical heating element; heat dissipating means mounted on and unitary with each heating element; said heat dissipating means including fin means extending transversely of the respective heating element and longitudinally of said conduit means; and means fastening together adjacent ones of said sectional units so that said sectional units form said conduit means providing a continuous passage through which may be passed and into contact with sai i heating elements.

iii. Ellectricel tretus, comprising: conduit leans constructed and arranged to proa fo fluid flowing tlierethrough; an elongated eie element having a body portion disposed within conduit means transversely of the path. provided for fluid flow and spaced from a wall of said conduit means; heat means mounted on and unitary with said heating element, said heat dissipating means comprising transverse fin means spaced longitudinaiiy heating element and extending transversely across said space from said body portion to wall; and means permanently fastening to said wail at least some of the ends oi said he means contacting said wall.

29. Electrical heating apparatus, comprising: conduit means including a plurality of sectional units constructed and arranged to provide a path for fluid flow; each of said sectional units having wall surfaces serving to guide fluid flowing through the respective sections, and each of said sectional units having disposed therein and unitary therewith at least one electrical heating element in the path provided for fluid flow; transverse flanges on adjacent units at the adjacent ends of said wall surfaces of adjacent units; and means fastening together adjacent ones of said flanges on adjacent units so that said wall surfaces provide a continuous passage through which fluid may be passed and guided by said wall surfaces into contact with said heating elements.

21, Electrical heating apparatus, comprising: a tube section for use in series with another tube section to form a sectionalized tube providing a path for fluid flowing therethrough in the direction of the longitudinal axis of the sectionallzed tube; an electrical heating element disposed within said tube section in the path provided for fluid flow; said tube section and said heating element being so constructed and arranged that they form a unitary structure; said tube section terminating at its opposite longitudinal axial ends so as to provide end openings the planes of which are respectively transverse to the longitudinal axis of said tube. section; and said tube section at said ends being so constructed and arranged that it may be fastened in longitudinal endwise abutment to another tube section having a cooperating open end of matching cross-sectional outline and forming a continuation of said first named tube section.

22. Electrical heating apparatus, comprising: a. sectionalized tube providing a path for fluid flow therethrough in the direction of the longitudinal axis of said sectionalized tube; said sectionalized tube including a plurality of tube sections, each providing a section of said path, each tube section terminating at its opposite longitudinal axial ends so as to provide an entrance opening and a discharge opening; the planes of which end openings are respectively transverse to the longitudinal axis of the tube section at the respective said ends of the tube section, adjacent a tube sections having their discharge and entrance ends oi! matching cross-sectional outline and in cooperating longitudinal endwise abutment; each tube section having disposed therein an electrical heating element in the path provided for fluid flow; each tube section and respective heating element disposed therein being so constructed and arranged as to form an individual unitary structure; and means for fastening together ad- Jacent abutting ones of said tube sections.

ERNEST N. CALHOUN. 

